Manufacture of glass.



EUGENE CORNELIUS SULLIVAN, OF CORNING', YDRK.

MANUFACTURE OF GLASS.

No Drawing.

Specification of Letters Patent.

Application filed July 12. 1909.

Patented Apr. 25, 1911.. Serial No. 507,105.

To all whom it may concern.-

Be it. known that l, .l hunmu C(JRXELIUS Suntan-us, a citizen of the United States, residing at Corning county of Steuben, and State of York, have invented certain new and useful improvements in the Mannfacture of Glass; and I do hereby declare the following: to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it ap 'ierlains to make and use the same.

As is connnonly knouui, lead glass is glass containing up to fifty per cent. of lead oxid, unhined with silica (Si(),) and alkali, such as potassa (K 0), and is at present made by melting together lead oxid (either in the form of lithargre, (Pbtl) or ruinium, (l"h,,(),) with a pure sand and potash. I'Ihe onids of lead used for this purpose must be of a special purity, being made from special brands of best refined lead, and they c01nmand a high price. The manufacture of these oxids is a tedious and costly operatioi'l, deleterious to the health of the workmen. The handling and mixing;- of the lead onids with. the glass forming the charge also accompanied by the escape oflead oxid dust into the air, so that poisoning of the work men is not infrequent. Furthermore, the lead oxids do not dissolve rapidly and uniformly in the glass mixture and it requires the highest skill of the nielter to produce glass of fairly homogeneous composition and density.

The. object of the present invention is to incorporate lead into glass in the manufacture of lead glass, by using as the direct source of the lead, the cheap natural lead sulfid or galena (PbS), the most common ore of lead. As at present practiced, this ore is first reduced by a complicated set of metallurgical reactions to crude metallic lead; the latter is then refined either by fire processes or by electrical refining; the refined lead of high purity is then oxidized in special furnaces to lead oxid; and finally, the latter is mixed with glass forming: materials and melted together therewith to form lead glass as hereinbefore indicated.

My invention consists in first purifying, if necessary, the native lead sulfid ore galena) by washing, jigging, or other meinvolves no operation not crnnmonly known ing furnace, at the speed and temperature best. adapted torremoving' the sulfur most completely from the roasted material. I have found. for instance, that by hand roast-- ing a. mixtiu'e of three parts by weight of sand to one part by weight of g .lena in a reverheramry furnace, at a temperature risin o; to between 900 degrees and 1,000 degrees ccntigrade, and allowing the roasting" material to remain about twenty-fern hours in the furnace, with stirring at intervals of one hour, the sulfur remaining has been reduced to-0.05,per-cent., furnishing a practically pure lead product, pure enough to satisfy the very exacting; requirements of thelead glass nlalier.

I believe-that the strict conditions as to purity of the materials, and the high elimination of sulfur which my experimcntshave shown possible, areoutside of any recorded facts or experience in the metallurgical roastingof galena ore, and that I am the first to demonstrate that a lead-bearing material, p actically free from sulfur and sufiiciently pure for glass making. purposes, can be practically produced in the "manner described.

The lead-bearing substance, which I thus produce, is of a granular, non-dusty and sintered form. The small grains appear to be almost entirelyof quartz with a more or less irregularly distributed pebble-dash surface of-lead silicate. Some of the grains carry more of silicate than others and the silicate shades into the quartz rather gradi'ially, showing' all gradations of concentration. At the outer surface the silieateds apparcntly a pure component, judging from itsrefractive index, and the roasted product as a whole appears clean, and sufiiciently uniform for the purposes intended.

In compounding, and thereafter handling, storing, or transporting from one'part of the works to another a batch made with lead silicate, the mixture isfound to take on and maintain greater uniformity of distribution of the ingredients throughout the mass than when litharge is employed; forthe Lennon, that the specific gravity of the lead silicate more nearly corresponds to that of the remaining constituents.

A further advantage to be gained by the use of lead silicate in the manufacture of lead glass is that it is free from metallic lead, which is present up to one-half of one per cent. and more even in the best commercial litharee, and also to some extent in minium. This metallic lead tends to give the glass a darker color, and. furthermore. it tends to shorten the life of the glassanelting pot by eating: through the pot wall.

Throughout the entire operation. there is no grinding, mixing or handling of litharge or minium, thus avoiding lead oxid dust from those sources and its poisonous effects on the workmen. There are, moreover, only two operations necessary in passing from the purified ore to the glass. I believe, moreover, that the glass produced is more homogeneous than if made by attempting to dissolve free lead oXid in glass.

In manufacturing lead. glass containing lime, the lime (used as lime, limestone, or gypsum) may be mixed with the silica and lead sullirl and thus participate in the roasting operation; or the lime, limestone or gypsum alone may be mixed with the lead sulfid and roasted therewith, the silica being introduced later in the fusion operation; or the lime, limestone or gypsum may be excluded from the roasting operation and used. only in the final fusion to glass. Suel'i variations fall within the generic principle of th'eprocess devised by me, which is essentially 'to roast the lead sulfid, thoroughly mixed with a diiiicultly fusible substance, under test conditions as to purity of the roasted product, and then to use this roasted product in glass makiny.

Having thus described my inventionhvhat I claim isz 1. The method of manufacturing glass, consisting in oasting a i'nixture of lead sulfid and a ditlicultly fusible substance appro priate to the manufacture of lead glass, adding to the productof the roasting operation the other ingredients desirable in such manufacture, and fusing, the final mixture to a glass: substantially as described.

2. The method of manufacturing glass, consisting in roasting a mixture of lead sulfid andsiliea, adding to he product of the roasting operation the other ingredients desirable in the manufacture of lead :rlass, and fusing the final mixture to a glass; substantially as described.

3. The method of manufacturing glass,

consisting in roasting a mixture of lead sulfid, a silicious substance and a (Hlfiilll'l'LCOlllpound (such as lime, lil'l'lGSt'OflG, or gypsun'i),

lead glass, and fusing the final mixture to a glass; substantially as described.

in testimony whereof I afiix my signature, in presence. of two witnesses.

EUGENE CORNELIUS SULLIVAN. lVitncsses Janus HoAnn,

MICHAEL J. Moore 

